The present invention relates to an energy-conserving triggered ID system and method, and in particular, it concerns a system and method for an ID reader having long standby and overall long battery life.
In the description and claims with follow hereinbelow, the expression “ID system” is intended to mean any system that can discriminate a specific user and/or some general system commands (such as, but not limited to “on”, “off”, “pause”, and “resume”) from a user of the system. Typically, the ID system must initially identify/verify the user in order to subsequently receive commands from the user. Identification, verification, and/or discrimination may be effected by wired or wireless means.
A radio frequency identification (RFID) tag is an example of a component of a prior art ID system employing a wireless means. When interrogated by a reading device (another component of a prior art ID system) which is also denoted as an “interrogator” or as a “reader”, the RFID tag reflects or retransmits a radio frequency signal to return an encoded identification number or identifier to the interrogator. Some typical examples of RFID tag applications are: collection of highway and bridge tolls; worker identification as they enter and exit buildings; management of alarm systems; etc. In the case of toll collection, the RFID tag is positioned on a user's vehicle to respond to an interrogation signal as the vehicle passes through a toll collection point. An interrogator, communicating with a computer, reads and subsequently processes the tag identification number, which is in turn used to charge a toll to the user's credit card or other account.
Prior art RFID tag devices employ a number of optional technologies, some employing some type of on-board circuitry. A most daunting problem with such RFID tags is the need for DC power for the circuitry. The combination of environmental issues coupled with severe constraints on costs, size and weight usually requires that the tag not have a battery or other onboard power source. The only generally useable solution in this case is to obtain DC power by converting RF power received from the tag reader signal into DC power within the tag. In the specification and the claims with follow, a tag without a battery or other onboard power source is called a “passive tag” or employing the “passive method”.
Bauchaud et al, in US Patent Publication no. 20080084276, whose disclosure is incorporated herein by reference, describes a radio frequency identification (RFID) tag and a method and system for communicating with the RFID tag. An electromagnetic radio frequency signal is transmitted from an interrogator to the REID tag. The interrogator receives, from the RFID tag, a response signal including third data being the first data or a combination of the first data and the second data. The interrogator extracts the third data from the response signal. A default value equal to the combination of the first data and the second data is stored in the interrogator. If the interrogator determines that the third data is unequal/equal to the default value, then a screen of the interrogator displays that the RFID tag is enabled/not enabled.
Passive tags as described hereinabove depend on the tag receiving interrogation and subsequent powering signals from the reader/interrogator. Virtually all ID systems employ a stationary reader/interrogator, which, in addition to communicating with the passive tag, frequently has additional communications functionality with one or more systems. Interrogators are typically powered by mains power to provide sufficient/unlimited power for interrogation, communication, and other functions. In such cases, the interrogation signal, as well as other communications functions, may be operated nearly continuously—as specific interrogator power consumption is of marginal or of no interest in terms of the overall ID system operation.
However, there is may be a need for an interrogator to be remotely located and/or to be installed where there is no available mains power source; meaning the interrogator has a self-contained power source, such as a battery. Such installations also have significant cost advantages in that installation is quick and very flexible, in virtually any location. However, a battery-powered integrator has constraints on its operation to conserve battery power and ensure long operation life. One example of such a constraint is that interrogation and other signals must be controlled/minimized to conserve power and extend battery life. Likewise, other types of interrogators and ID systems, working with RF energy and/or other communications means, wired and/or wireless, and working with any combination of battery and/or mains power, may be more efficient and/or more optimally operated if signals and operation parameters are likewise better controlled.
There is therefore a need for an energy-conserving D system that has long standby life [GT1]and overall long battery life.